Thread nipper



F. M. O'BRIEN THREAD NIFPER May 20, 1952 INVENTOR.`

Filed June 2l, 1949 Francis M. O'Brien wwhmqmwm,

ATTORNEYS Patented May 20, 1952 :UN ITE D- S PATE N Tf Y.F-1:' [C EWQJTHREAD NIPPER .Fr ancis M.( )?Brien`, St. Petersburg, Fla."ApplicationjJune 21, 1949,;Seria1N0...100,413

551 latim. (Cl.. 30\ -253) 'ine-common* with the. implementof..thalt;iprior patent; the present invention .aims v.toL-provide a .i

-` 'conventional scissors inlwhichaconcealedrspring r`functions-tcwmarintain the-cuttingbladesin an open positionA and toreturn theblades =.to` this `*Hopen position after each manualsactuation to closethe bladesupon the thread; =.thler.ebeing also-'included alimit-StOp-toreStriCt.theextreme *movements of lthe scissors blades. iniboth-.open and closedlpositions.

- In the drawingswherein the symbols refer to likeor correspondingpartsthroughout the sevq eralviews,

`: Figure 1 is aperspective View of a threadnipper constructed inaccordance with the present invention and shown held in a position ofoperation.

f Figure 2 is a side elevation, taken onan enl larged scale of thedevice in normal open position.

- in -thepriorpatent referred to `the pivot-'C on 1 which the blades AandBrelativelytrock is displaced -fromall partsof--the springieand-.particu- -larly and critically from the hinge .portioni of thespring -which connects the Atvvoarms of; the, spring and about; whichthesearms movea in thegiexing l of the spring. L `This Aoifsetting.ofthespring. hinge from `the-blade pivotputsatwisting moQn and Figure 3 is alongitudinal section taken on the line 3 3 in Figure 2 and Fig-ure 4 isan explodedviewshowing in perspective theblades, spring and pivot bolt'Iseparated.

Reierring more particularly to the drawings,

It and-Il I represent the twoblades or members constituting the scissorsand having the cutting edges I2 and I3 respectively.v The outer edges ofa-*strainon theientiresspring durngjhe. Operation A f of the-threadnipperxwhichshortenstherli@ and actually impairs :the action;of the;spring.

Anobject of .the invention; is. to soleorganize andi-reconstruct the.parts I;of1;the .blades which reinge: is brought into `.coincidence-Withfthe pivot.

vdesirable.twistingtof theaspringparts landstrain f mwhichfthe same-hasibeenheretoiere Subisted f to revise f It .isanother objectoftheainvention the .formioi spring over that disclosed in e =prioroffioisetlends-jof suchyhelix; this vfeaturefpf ima helical Spring,butWhere-the spring hinge'A is coa: post or bearing- 4shaftffor .thecoil, supDQrting.

fThis. new. -location ,of ,the .Spring-:01kg QmmOn theblad e s oppositethecutting edges areflared orotherwise operated uponA to produce thepads I4 and 151er the comfort of the nger or thumb .i y ywhen used `incompressingithe scissors.

. '1 -he two blades I0 and I I are pivoted together bythe t)grrivotscrewI6for other suitable means, the

vhead of Whichts against one of the members I I f 1 and alsothrough aperforation IBin the .other center'with .the fpivat: point eliminatesthe un-.

memberor blade I0. The pivot bolt I6 is vprovided With an outerthreadedportion I9 and an At least a part o f the outer threaded portion I9projects beyond the outer face of the blade or member IB Where thesamereceives a nut 2| for binding the p ivot bolt I6 in place.

As shown more particularlyV in Figure 4 the blade I I jisformed with apartial socket 22 which 1 .is adapted to overlie and complement asimilar incident with .the :blade-pivot that 'helical form`offspringhingecooperateswith the pivotpin to` enablethe pivotpin-to passthroughthehelix as iff andfholding rthe,SpringinpIace andgrendering pthe...action. of .the -assembly-lmuch smoother and snappier, and also.requiring less .ngerpressure onthe DartV of the operatortoclosethejnippen.

ordinary quickness.

A further object of the inventiony i s=-to'j`p1ovide i( while assuringthat .the blades 0pm' w-ith"extra'- partial socket `23 in thecompanionblade I0; it

` beingunderstood that these sockets are made in vthe mutually innerfaces of the blades I I and I Il and thatwhen ,these blades areassembled together thefsockets 22 and 23 .will mate and produceav-closed cavity coaxial with the perforations I'I, I8 andcoaxial withvthe axis of the pivot bolt I6. The sockets22, 23 communicate withelongated recesses 24 and-25 respectively inthe inner faces `ofthebladesII and I0 and these recesses,

like the sockets-22 and23 openoutontheinner l'13a thread nipper ofvthe'character above'describedi With the foregoing and other objects. inview, :atheinventiongwillbe more fully described hereinafter, and:willi-be,more1pa1ticularly; pointed out E i intheclaim appended hereto.

-- in 4"which the reconstruction andrearrangement facesot the V bladesbut are concealed by the outer v portions loftheblades.' f Theserecessesextend off theirv `vrespective' .sockets Y in directionslongitudinally of the blades which are rangularf to one another when theblades are assembled together. In

Figure-1.4 y.the no n gitudinai.direction@ bothreisshown:inclininggnpwardly tov .fromtherespectvesockas22 and 2 3butwhenthe, blade I I isturned over tomate with its companion blade Ithe recess 24 will not accurately mate throughout its area with therecess 25 but will be slightly angularly offset therefrom.

The recesses 24 and 25 preferably taper in the direction away from thesockets 22, 23 and cavities or bores 26 and 21 are made in the blades II and I0 respectively communicating with the upper narrower ends of therecesses 24 and 25.

A spring helix 28 is adapted to be received in the sockets 22, 23 andabout the shank of the pivot bolt I6. This helix 28 has spring arms 29and 39. One spring arm comes tangentially off vallargare one end of thehelix 28 while the other spring arm 30 comes tangentially off the otherend of the helix. The tangent points are preferably substantiallydiametrically offset one another so that at the end convolutions of thespring helix or spring hinge 28 the arms 29, 30 are in relativelyangularly displaced positions with the arms 29 and 30 preferablydiverging to such an extent that when assembling these arms 29 and 30will have to be moved together on the circle of the helix 28 in order tocause both such spring arms to register with the recesses 24 and 25which are designed to receive these spring arms with the ,terminal endsof the arms tted into the cavities 2B and 21. This helix or coil stackis preferably formed from a single vstrand of resilient wire coiledintermediate its ends into a suitable number of convolutions. The springis wholly concealed and protected by the blades I0 and II. The potentialenergy and torsion given the spring is such that when the same is in theposition shown in Figure 4 alone and apart from the pocketedconstruction of the blades vIl! and Il, the spring arms 29 and -30 willinherently seek an angular outstretched position which is greater thanthe distance by which the recesses 24, 25 are offset. This arrangementrequires that the spring arms 29, 30 be moved angularly together tobring the same in alignment with the recesses 24, 25 in Vwhich they areinserted and this action places the helix 28 under the necessarytension. The spring tends to open at all'times and to spread the springarms 29 and 30 which react against the side walls of the recesses 24, 25and also against the walls of the cavities 26, 21, thus biasing theblades I0 and II to the open position shown in Figure 2.

By inserting a finger' through the finger hold 3I and otherwise graspingthe device'in the manner generally indicated in Figure 1 and with thethumb and first finger exerting pressure on the pads I4 andV I5, thecutting edges I2 and I3 may be closed by manual pressure against theinfluence of the torsion spring. During such movement the spring arms29, 39 will be rotated to gether to further wind the spring convolutions28 and to store energy in the spring. When released the spring willreact to force the scissors blades I9 and II into the open position.

A stop screw or other abutment 32 may be carried by one of the blades,for instance the blade In in position to occupy a stop socket 33produced in the inner face of the companion blade II; it beingunderstood that the diameter of the socket 33 exceeds that of the stopprojection 32 by an amount preselected to limit the through or relativeangular movement of the blades I0 and I I in both opening and closingmovements.

In assembly, the two blades are brought together on the spring with theends of the spring arms 29 and 30 being slid upwardly into the cavities21, 25 so that the spring arms fall into the recesses 25, 24 while thespring helix or hinge is received in the socket 23, 22. The pivot boltI6 is then inserted through the openings I1, I8 and it will be foundthat the open or hollow spring helix or hinge 28 is in registry with theopenings I1, I8 so that the bolt I8 is also received therethrough. Thenut 2l is thereupon run upon the projecting end of the bolt I9 andtightened up, the nut 2I being larger in diameter than the opening I8and therefore abutting against the outside face of the blade I0. The nut2I is tightened so that the correct cutting pressure is exerted on thecutting edges I2 and I3. This cutting pressure or shear is heightened bythe fact that the coil stack 28 engaging against the inner walls of thesockets 23, 22 tends to move the blades I0 and II apart. this tendencybeing overcome by tightening the nut 2|. The nut 2I and its companionbolt I8 therefore constitute not merely a form fastening or a pivot axisfor the blades but the arrangement also serves to adjust the tension ofthe coil spring 28 insofar as it tends to move the blades apart andplace tension shear on the cutting edges I2, I3. Thus the form of helix28 has a double function, namely to place the spring arms 29 and 30under a tension in a torsional or rotary sense to open the blades afterrelease following each closing operation; but the spring coil is also ofsuch axial length that it is put under compression when the nut 2I isfinally tightened and its tendency to react and expand axially causesthe blades to tend to move apart and thus places shear tension on thecutting edges I2, I3. Where the spring helix or hinge 28 is offset fromthe pivot axis it is necessary to insert the spring, hold the bladestogether with the openings in line and insert the bolt I6. This isdifficult because the spring tends to push the blades apart.

With the new assembly in which the helix 28 is coaxial with the pivot I6the assembly of the nipper is easier because the spring may be held bythe bolt during the assembling operation. In other words the bolt I6 maybe tted through the perforation I1 and the spring helix 28 entered overthe shank of the bolt and the threaded end I9 of the bolt afterwardspassed through the opposed perforation I8 of the other blade I0, the nut2I being subsequently run upon the outer end of this threaded portionI9. The spring armsl 29 and 30 are of course sufllciently flexible to bebent or curved momentarily out of shape for the purpose of fitting theterminals thereof into the cavities 26, 21.

The reorganization and reconstruction of the device with the axis of thecoil helix 28 and that of the pivot bolt I8 coincident has greatlyimproved the action of the thread nipper itself and in addition greatlyprolongs the life of the spring for the reason that the bolt passingthrough the hollow helix itself adds considerable support to thismember. The new method of construction also facilitates the replacementof springs when necessary.

The helix 28 preferably ts over the plain unthreaded portion of thepivot bolt I6 so that changes as may come within the scope of thefollowing claim.

What I claim is:

A tool of the character described comprising a pair of blades havingcomplementary cutting ends and opposing hinged ends, said last endsbeing formed with registering transverse openings and partial socketsformed on the inner faces of the ends and arranged coaxial with theopenings, said sockets communicating with elongated recesses Which taperlongitudinally of the blades from the sockets toward the cutting ends,said blades having longitudinally disposed bores communicating with thetapered ends of the recesses spaced from the openings, a spring having ahelix coil and arms extending outwardly from the helix, said coil beingseated in the sockets and arranged transversely between the blades withits ends disposed in the recesses and received at their free terminalsin the bores,

6 the opening of said coil being aligned with the openings in theblades, a pivot passing through the openings and said coil, and meanscarried by the pivot for clamping the blades together.

v FRANCIS M. OBRIEN.

`ile of this patent:

UNITED STATES PATENTS Number Name Date '772,275 Downing Oct. 11, 19041,186,235 Schrade June 6, 1916 1,299,104 Arnold Apr. 1, 1919 2,392,118Cacarillo Jan. 1, 1946 FOREIGN PATENTS Number Country Date 276,262Germany July 8, 1914

